Bump mockito-core from 2.23.4 to 2.28.2

Bumps [mockito-core](https://github.com/mockito/mockito) from 2.23.4 to 2.28.2.
- [Release notes](https://github.com/mockito/mockito/releases)
- [Commits](mockito/mockito@v2.23.4...v2.28.2)

Author: dependabot-preview[bot]

build.gradle

@@ -57,7 +57,7 @@ dependencies {
 
   testCompile group: 'cd.go.plugin', name: 'go-plugin-api', version: '17.7.0'
   testCompile group: 'junit', name: 'junit', version: '4.12'
-  testCompile group: 'org.mockito', name: 'mockito-core', version: '2.23.4'
+  testCompile group: 'org.mockito', name: 'mockito-core', version: '2.28.2'
   testCompile group: 'org.hamcrest', name: 'hamcrest-library', version: '2.1'
   testCompile group: 'org.skyscreamer', name: 'jsonassert', version: '1.5.0'
   testCompile group: 'org.jsoup', name: 'jsoup', version: '1.11.3'